The controller design aspect for nonlinear systems subjected to parametric and nonparametric uncertainties has always been a challenging task. Adaptive control and Robust control are the two popular control strategies to deal with uncertain nonlinear systems. In case of adaptive control, online computation of the unknown system parameters and controller gains for complex systems is significantly intensive [1]}. On the other front, robust control reduces computation burden for complex systems compared to adaptive control, while requiring a predefined upper bound on the uncertainties.
However, in practice it is not always possible to estimate a prior uncertainty bound due to the effect of unmodelled dynamics. Again, to increase the operating region of the controller, often higher uncertainty bounds are assumed. This in turn leads to overestimation of switching gain and high control effort [2]}.
